This invention relates to a gelled microemulsion cleaning composition and to processes for manufacture and use thereof. More particularly, it relates to a stable gelled microemulsion cleaning composition in concentrated form which is especially effective to clean oily and greasy soils from vertical surfaces such as bathroom fixtures and walls, leaving such surfaces clean and shiny without the need for extensive rinsing thereof. The described compositions comprise a mixture of anionic surfactants, a water insoluble organic compound having an .delta..sub.H of about 0 to about 1 (MPa).sup.1/2, .delta..sub.d of about 14 to about 18 (MPa).sup.1/2, and .delta..sub.p of about 0 to about 2 (MPa).sup.1/2, water and a suitable co-surfactant system, which co-surfactant system adjusts the interface conformation to reduce interfacial tension at interfaces between dispersed and continuous phases of the emulsion of the surfactants, produces a stable gelled microemulsion at room temperature. When the pH of the gelled microemulsion is on the acid side, preferably in the range of 1 to 4, the invented compositions are useful for removing lime scale and soap scum from hard substrates.
Liquid detergent compositions, usually in solution or emulsion form, have been employed as all-purpose detergents and have been suggested for cleaning hard surfaces such as painted woodwork, bathtubs, sinks, tile floors, tiled walls, linoleum, paneling and washable wallpaper. Many such preparations, such as those described in U.S. Pat. No's. 2,560,839, 3,234,138, and 3,350,319 and British Patent Specification No. 1223739, include substantial proportions of inorganic phosphate builder salts, the presence of which can sometimes be found objectionable for environmental reasons and also because they necessitate thorough rinsing of the liquid detergent from the cleaned surface to avoid the presence of noticeable depositings of phosphate thereon. In U.S. Pat. No's. 4,017,409 and 4,244,840 liquid detergents of reduced phosphate builder salt contents have been described but such may still require rinsing or can include enough phosphate to be environmentally objectionable. Some liquid detergents have been made which are phosphate-free, such as those described in U.S. Pat. No. 3,935,130, but these normally include higher percentages of synthetic organic detergent which increased detergent content may be objectionable due to excessive foaming during use that can result from its presence. The previously described liquid detergent compositions are emulsions but are not disclosed to be pseudo microemulsions like those of the present invention.
Microemulsions have been disclosed in varic, us patents and patent applications for liquid detergent compositions which may be useful as hard surface cleaners or all-purpose cleaners, and such compositions have sometimes included detergent, solvent, water and a co-surfactant. Among such disclosures are European Patent Specification No's. 0137615, 0137616, and 0160762, and U.S. Pat. No. 4,561,448, all of which describe employing at least 5% by weight of the solvent in the compositions. The use of magnesium salts to improve grease removing performance of solvents in microemulsion liquid detergent compositions is mentioned in British Patent Specification No. 2144763. Other patents on liquid detergent cleaning compositions in microemulsion form are U.S. Pat. No's. 3,723,330, 4,472,291, and 4,540,448. Additional formulas of liquid detergent compositions in emulsion form which include hydrocarbons, such as terpenes, are disclosed in British Patent Specifications No's. 1603047 and 2033421, European Specification No. 0080749, and U.S. Pat. No's. 4,017,409, 4,414,128, and 4,540,505. However, the presence of builder salt in such compositions, especially in the presence of magnesium compounds, tends to destabilize the microemulsions and therefore such builders are considered to be undesirable.
Although the cited prior art relates to liquid all-purpose detergent compositions in emulsion form and although various components of the present compositions are mentioned in the art, it is considered that the art does not anticipate or make obvious the gelled microemulsions disclosed and claimed herein. In accordance with the present invention a stable gelled microemulsion cleaning composition, which is in concentrated form, comprises at least two different anionic synthetic organic detergent, a water insoluble organic compound, water and a co-surfactant system, which co-surfactant system adjusts interfacial conformation to reduce interfacial tension at interfaces between dispersed and continuous phases of an emulsion of said surfactants, and produces a stable concentrated gelled microemulsion which is stable at temperatures in the range of 5.degree. to 50.degree. C. and which has a pH in the range of 1 to 11. Such concentrated gelled microemulsions are dilutable with water to at least five times their weight, to produce diluted liquid detergent compositions which are often also stable aqueous pseudo microemulsions which are useful as all-purpose cleaning compositions. Both the concentrated gelled and diluted compositions are effective for cleaning oily and greasy soils from substrates, and when the compositions are acidic they are also useful to remove lime scale and soap scum from hard surfaces, such as bathroom fixtures, floors and walls.
In addition to the gelled microemulsion concentrates, the present invention also relates to dilute pseudo microemulsions to processes for manufacturing such pseudo microemulsions and to processes for cleaning surfaces with them.